• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.203-216
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• 1994

The laboratory methods for compaction of soil (KSF 2312) and for moisture of soil (KSF 2306) in combination with the soil density in place by the sand-cone method (KSF 2311) are generally used for compaction control of soils. However, these methods have limitations in number of test and in accuracy. ]n addition, they are time-consuming. Therefore, they are not adequate for speedy control of embankment compaction in a project with huge amount of earthwork. The RI (Radioisotope) gauges for measurement of soil density and/or of soil moisture are widely used for the compaction control of soils in many countries. But in Korea, they have had a limited usage and available informations for uses of RI gauges are insufficient. Therefore, this study promotes efficient and safe use of RI gauges in geotechnical engineering. In this paper, fundamental aspects such as the priciples of RI gauges, gauge inspection techniques and the applicability and limitations of RI gauges for field usage were reviewed. And a new calibration curves suitable for the Korean soils were suggested.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.149-160
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• 2008

Offshore pile foundations are prone to lateral soil pressures resulting from embankment construction for the reclamation on deepwater soft clay. Since the 1990s, offshore reclamation has actively progressed in Korea, connecting with the development of Songdo newtown, Incheon newport, and Busan newport representatively. Special attention has been given to lateral soil-structure interaction problems related to passively-loaded offshore pile foundations. Based on a plane strain large deformation finite element (LDFE) approach, this paper presents the results of investigation into undrained (short-term) and drained (long-term) behavior of passively-loaded offshore pile foundations. This study examines the effects of major factors, such as soil profile, pile head boundary condition, magnitude of embankment load, and average degree of consolidation. The results allowed quantification of differences in the magnitude of lateral soil pressure acting on the piles between undrained and drained phases.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.03a
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• pp.31-42
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• 1994

In this paper, a case study was presented to analyze the lateral movement of abutment founded on the soft soil with steel pile foundations and was to propose its remedial methods. The main reason for the displacement was due to the lack of the lateral bearing capacity of piles and even more seriously the lateral movement of the soil arising from the construction of as embankment behind the abutment. This project showed that the passive state as well as the active state of piles must be considered for the proper design of abutment foundations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.377-386
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• 2010

This study was conducted to find out the characteristics of the expanded road embankment constructed by the lightweight air-mixed soil (slurry density $10kN/m^3$) for a short-term without any ground improvement. Compression strength, capillary rise height of the lightweight air-mixed soil and settlement behavior of soft ground were studied. Compression strengths of the specimens sampled at the site after 1 and 5 months of construction were all satisfied the required strength 500 kPa. However, it was not convinced the homogeneity construction, because the values of strength were depending on the sampled location. Also, strength difference between laboratory and site specimens were found about 19%, and thus it should be considered for mixing design. Capillary rise reached about 20 cm for 70 hours because of a numerous tiny pores existed inside the lightweight air-mixed soil. Relationship between settlement and time of the soft ground placed underneath the expanded embankment was estimated by using the measured data and back analysis technique. The current average consolidation ratio and the final settlement after 120 months later were estimated about 32% and 4.5cm, respectively. This settlement is much less value than the allowable settlement 10cm for this structure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.427-434
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• 2000

This paper presents a computer program for a 2-D fluid-structure-soil interaction analysis. With this computer program the fluid can be modeled by a spurious free 4-node displacement-based fluid element which uses rotational penalty and mass projection technique in conjunction with the one point reduced integration scheme to remove the spurious zero energy modes. The structure and near field soil are discretized by the standard finite elements while the unbounded far field soil are discretized by the standard finite elements while the unbounded far field soil is represented by the frequency dependent dynamic infinite elements. Sine this method models directly the fluid-structure-soil system it can be applied to the dynamci analysis of 2-D liquid storage structure with complex geometry. For the purpose of verification dynamic analyses for tanks on a rigid foundation and on compliant embankment are carried out. Comparison of the present results with those by ANSYS program shows good agreement.

• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.207-220
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• 1999

Model tests were performed to investigate the failure modes in embankments on soft ground supported by piles with cap beams. In the model tests, Jumunjin standard sand was placed on simulated cap beams and soft ground. The cap beams are placed perpendicular to the longitudinal axis of the embankment. The colored sand and the Jmniin standard sand were placed one after the other above cap beams and soft ground to make lateral stripes with 3mm thickness in the embarkment. The colored sand was prepared by coating the Jumunjin sand with black lead powder. The photographs illustrate the two characteristic modes of failure in embarkments. One is the soil arching failure and the other is the punching shear failure. The failure mode depends on the height of embankment and the space between cap beams. That is, if the embankment is high enough compared with the space between cap beams, it will fail in arching failure. On the other hand if the embarkment is relatively low or the space between piles is too wide, it will fail in punching shear failure. The soil arching develops in embarkment as a semicylindrical arch with a thickness equal to the width of the cap beam. And the soil wedge developed above the cap beams remains intact during both arching and punching failures. The boundary of punching shear failure of the displaced soil mass can be defined on the basis of observation of the photographs.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1287-1296
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• 2007

Recently, the high speed railway comes into the spotlight as the important and convenient traffic infrastructure. In Korea, Kyung-Bu high speed train service began in about 400km section at 2004, and the Ho-Nam high speed railway will be constructed by 2017. The high speed train will run with a design maximum speed of 300-350km/hr. Since the trains are operated at high speed, the differential settlement of subgrade under the rail is able to cause a fatal disaster. Therefore, the differential settlement of the embankment must be controlled with the greatest care. Furthermore, the characteristics and causes of settlements which occurred under construction and post-construction should be investigated. A considerable number of studies have been conducted on the settlement of the natural ground over the past several decades. But little attention has been given to the compression settlement of the embankment. The long-term settlement of compacted fills embankments is greatly influenced by the post-construction wetting. This is called 'hydro collapse' or 'wetting collapse'. In spite of little study for this wetting collapse problem, it has been recognized that the compressibility of compacted sands, gravels and rockfills exhibit low compressibility at low pressures, but there can be significant compression at high pressures due to grain crushing by several researchers(Marachi et al. 1969, Nobari and Duncan 1972, Noorany et al. 1994, Houston et al. 1993, Wu 2004). The characteristics of compression of fill materials depend on a number of factors such as soil/rock type, as-compacted moisture, density, stress level and wetting condition. Because of the complexity of these factors, it is not easy to predict quantitatively the amount of compression without extensive tests. Therefore, in this research I carried out the wetting collapse tests, with focusing in various soil/rock type, stress levels, wetting condition more closely.

• Geotechnical Engineering
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• v.4 no.1
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• pp.49-58
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• 1988

The stresses on the buried steel pipe under embankment are analysed by the elasto-plastic theory using FEM to study the influences of the geometry of soil-conduit pipe system and the elastic modulus of the fill on the pipe responses . The geometry of the system considered in this study includes the height of embankment, the thickness of the pipe, and the width and the depth of the trench . By comparing the stresses computed by Marston-Spangler's pipe theory with those obtained from the elasto-plastic theory, Marston-Spangler's theory was discussed and analysed . It is found that the stress distribution around the pipe by elasto- plastic analysis is similar to that by Spangler's flexible pipe theory when the geometrical ratio (diameter/thickness) of the steel pipe is 400. And Spangler's flexible pipe theory does not seem to be suitable to analyse the buried steel pipe of which the geometrical ratio is lower than 200. The vertical loads by the rigid pipe theory are always larger than those by the flexible pipe theory regardness of the variations in the geometry of soil-conduit pipe system considered above and the elastic modulus of the fill.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.29-37
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• 2013

In this study, we constructed the test embankment with four kinds of sections(2 kinds of bottom ash; tire shred-bottom ash mixture, weathered soil) in field and had been monitoring the behaviour of the test embankment and change of ground water quality for 1 year. In the geotechnical aspects, there was no relative difference of deformation in 4 test materials section and we could not see the possibility of the strength-reduction of coal ash materials by freezing inside of the embankment. In addition, no settlement was observed in the test sections because the base soil of the test sections was rigid enough that no consolidation was occurred. In the examination of water quality, all of the heavy metals and negative ions were detected below the drinking water standards except for sulfate($SO_4^{2-}$). In the beginning of measurement, higher concentrations of sulfate from 4 test sections were detected than drinking water standard for 20 days after beginning of the test but the concentrations decreased below the drinking water standard after 50 days after the tests.

• Journal of the Korean Geotechnical Society
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• v.22 no.3
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• pp.13-21
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• 2006

Geosynthetic damage has attracted a major attention since the introduction of geotextiles for civil engineering applications. In this study 3 pilot trial embankments were carried out to investigate the behaviours of reinforced embankments over soft cohesive soils and to find the optimum methodology of embankments over soft soils. As the seamed part of polyester mat (PET, tensile strength 15 ton) used in the first full-scale field test was ruptured under progressing rotational slope failure because of unexpectedly rapid construction of embankments, the excessive pore water pressures were measured. On the soil behavior where tension explosion of mat was continued, pore pressure larger than the one caused by embankment height was measured. Especially, at the depth of 5.0 m under the ground pore pressure increased over long term. It was discussed with respect to the height of embankment and heaving behavior of soft soils.